Along with the greatly increased activity centered around personal computer usage in recent years, and particularly due to the near explosive use of laptop, desktop, and notebook computers, there has arisen a corresponding increase in the need for mechanisms directed to facilitating proper viewing of their associated displays. The need for suitable user-controllable viewing angle adjustability of flat panel displays of the LCD and related types is especially acute as these small computers and their displays are used in a wider variety of environments. The use of these displays in homes, offices, or vehicles (trains, planes, etc.) presents previously unencountered difficulties caused by frequently changing viewing angles and ambient lighting conditions. Thus, a set of unique display device mounting conditions and requirements have emerged, some of which are exacerbated by the very light weight and high portability of the flat panel displays themselves. In short, the unusual needs for frequent and precise adjustability of flat panel displays requiring light user touch and high stability of the tilt angle settings present severe challenges for frictionally biased tilt setting mechanisms.
Descriptions of typical prior art approaches to user-operated display tilt devices may be found in a number of U.S. patents.
U.S. Pat. Nos. 5,333,356 to Katagiri and 4,770,382 to Lehti both disclose apparatus for controlling the viewing angles of display panels utilizing spring-biased mechanisms to impart frictional loading to their rotational elements. In the '832 patent, a supporting arm or rod applies variable tension via a pivot journal to a slide part on which a flat panel display is mounted. In the '356 patent, rotating friction is applied to a hinge pin-like pivot element via interiorly positioned frustro-conical surfaces. Both of these patents show the use of Belleville springs as part of their urging mechanisms.
U.S. Pat. No. 5,509,176 to Karl teaches an entirely different approach to flat panel viewing angle settings using a torque hinge wherein an interference fit of a coated shaft inserted within the housing cavity produces constant resistance through the hinge's range of motion. Coating materials are recited as being MCU foam, Teflon, or silicone.
Other U.S. patents of general interest for their early teachings of basic frictional hinge pin assemblies are U.S. Pat. Nos. 3,239,874 to Sperzel and 3,357,041 to Brueder. In the '874 patent, a screw plug presses directly against a single nylon block to urge a hinge pin against its housing sleeve to provide the controlled friction.
Therefore, it is clear that as the needs for precisely controllable and long service life frictional tilt mechanisms increase, there are significant improvements to existing devices yet to emerge. It is precisely these more stringent needs for operating smoothness coupled with long-term stability, as well as simple and precise user adjustability, that the present frictional tilt mechanism admirably provides.